Animate Mesh in a wavelike movement
You could use a sin() function and a driver to animate e.g. the X scale. In Object Properties under Transform for one of the cylinders, click the number in Scale: X and type in something like:

#1.0 + 0.2 * sin(frame * 2.0 * pi / 30.0)


That'll vary scale every 30 frames between 0.8 and 1.2. For later cylinders you can offset the phase a little:

#1.0 + 0.2 * sin((frame + 5) * 2.0 * pi / 30.0)


That'll put that cylinder 5 frames ahead in the animation.